PALEOENVIRONMENTAL IMPLICATIONS OF PALYNOMORPHS FROM THE PORTERS CREEK CLAY FORMATION (LATE PALEOCENE) OF SOUTHEAST MISSOURI

Well preserved palynomorphs occur in samples from the Late Paleocene Porters Creek Clay interval of BH-1 borehole in the Benton Hills of Southeast Missouri. Spores and pollen are the dominant palynomorphs recovered in the formation although their diversity and abundance fluctuate in the samples. They are more diverse and abundant in the basal samples and decrease up section. Marine palynomorphs (dinoflagellate cysts, acritarchs, and foraminifera linings) are relatively few in number toward the base of the interval, whereas they become more diverse and abundant in the middle of the formation. The upper most interval is completely barren. This pattern apparently records a marine transgression that was prevalent in the middle of the formation and is confirmed by clay mineralogy. The palynomorph assemblages are being compared with those from the upper Paleocene sediments in the U.S. Gulf Coast.